Zincophilic Sn sites induced the local ion enrichment for compact and homogenous growth of Zn biscuits in long-life Zn metal batteries

Abstract

The inevitable formation of zinc (Zn) dendrites and side reactions impede the practical applications of long-life and stable Zn metal batteries (ZMBs). Herein, a self-supporting and zincophilic skeleton, reduced copper foam containing Sn sites (R-CF@Sn), is constructed to induce dense and homogenous Zn growth for enhancing the performance of Zn metal anode and ZMBs. A facile and effective decoration of functional Sn coating not only exhibited a high Zn ion adsorption energy to promote the uniform distribution and local enrichment, but also guided the subsequent stable Zn nucleation and dense biscuit-like Zn metal development, which was substantiated by microscopy images. Due to the positive construction of zincophilic Sn layer and rough skeleton surface, the electrolyte wettability of R-CF@Sn was greatly improved compared to that of bare copper substrate. When applied for evaluating the coulombic efficiency (CE) performance, the R-CF@Sn skeleton showed a low nucleation overpotential of 6.6 mV and maintained a high average CE value of 98% for 400 cycles at 5 mA cm⁻². Moreover, a symmetric cell with R-CF@Sn plating with Zn metal of 3 mA h cm⁻² could deliver prolonged lifespans of 1600 h (1 mA cm⁻²) and 700 h (5 mA cm⁻²) at a plating/stripping capacity of 1 mA h cm⁻². The superior specific capacity delivery of the full cell with an MnO₂ cathode further indicates the positive effect of stabilizing the Zn metal anode possessed by the R-CF@Sn skeleton.